Method and apparatus for acknowledging SCell beam failure recovery request

ABSTRACT

A method for SCell BFR performed by a UE is provided. The method includes: transmitting, to a base station, a BFR MAC CE that includes a cell index of an SCell in which beam failure occurs and a new candidate beam index for the SCell, the transmission of the BFR MAC CE associated with a HARQ process having a HARQ process ID; and receiving, from the base station, a first DCI format that schedules a first PUSCH transmission with the HARQ process ID, the first DCI format indicating a toggled NDI value.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims the benefit of and priority ofprovisional U.S. Patent Application Ser. No. 62/806,083, filed on Feb.15, 2019, entitled “Mechanism for Ending SCell Beam Failure RecoveryProcedure,” (hereinafter referred to as “US76548 application”). Thedisclosure of the US76548 application is hereby incorporated fully byreference into the present application.

FIELD

The present disclosure generally relates to wireless communication, andmore particularly, to a method for beam failure recovery (BFR) incellular wireless communication networks.

BACKGROUND

Various efforts have been made to improve different aspects of wirelesscommunications, such as data rate, latency, reliability and mobility,for cellular wireless communication systems (e.g., fifth generation (5G)New Radio (NR)). For example, beam management introduced in a NR systemestablishes and retains a suitable beam pair link, specifically atransmitter-side beam direction and a corresponding receiver-side beamdirection that jointly provide good connectivity. In some cases,movements in the environment may lead to an established beam pair linkbeing rapidly blocked. In NR, a BFR procedure is introduced to handlesuch beam failure events. In addition, carrier aggregation (CA) issupported in NR. A Primary Cell (PCell) may operate in sub-6 GHzfrequency bands (Frequency Range 1, FR1) and a Secondary Cell (SCell)may operate in frequency bands above 24 GHz (Frequency Range 2, FR2).Beam failure (e.g. beam blockage) happens more frequently in FR2 becauseof the channel characteristics of the millimeter wave propagation.Therefore, there is a need in the industry for an improved and efficientmechanism for a user equipment (UE) to handle beam failure recovery inthe SCell.

SUMMARY

The present disclosure is directed to a method for SCell BFR performedby a UE in the next generation wireless communication networks.

According to an aspect of the present disclosure, a UE for performingSCell BFR is provided. The UE includes one or more non-transitorycomputer-readable media having computer-executable instructions embodiedthereon and at least one processor coupled to the one or morenon-transitory computer-readable media. The at least one processor isconfigured to execute the computer-executable instructions to: transmit,to a base station, a BFR Medium Access Control (MAC) Control Element(CE) that includes a cell index of an SCell in which beam failure occursand a new candidate beam index for the S Cell, the transmission of theBFR MAC CE associated with a Hybrid Automatic Repeat Request (HARQ)process having a HARQ process identifier (ID); and receive, from thebase station, a first Downlink Control Information (DCI) format thatschedules a first Physical Uplink Shared Channel (PUSCH) transmissionwith the HARQ process ID, the first DCI format indicating a toggled NewData Indicator (NDI) value.

According to another aspect of the present disclosure, a method forSCell BFR performed by a UE is provided. The method includes:transmitting, to a base station, a BFR MAC CE that includes a cell indexof an SCell in which beam failure occurs and a new candidate beam indexfor the SCell, the transmission of the BFR MAC CE associated with a HARQprocess having a HARQ process ID; and receiving, from the base station,a first DCI format that schedules a first PUSCH transmission with theHARQ process ID, the first DCI format indicating a toggled NDI value.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the example disclosure are best understood from the followingdetailed description when read with the accompanying figures. Variousfeatures are not drawn to scale. Dimensions of various features may bearbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a flowchart of an example method for beam failure recoveryperformed by a UE, according to an example implementation of the presentapplication.

FIG. 2 is a flowchart of an example method for SCell BFR performed by aUE, according to an example implementation of the present application.

FIG. 3 includes a diagram illustrating an example method for an SCellBFR procedure, according to an example implementation of the presentapplication.

FIG. 4 is a flowchart of an example method for SCell BFR when a UE isconfigured with a BFR timer, according to an example implementation ofthe present application.

FIG. 5 includes a diagram illustrating an example cross-carrierscheduling scenario, a according to an example implementation of thepresent application.

FIG. 6 is a block diagram illustrating a node for wirelesscommunication, in accordance with various aspects of the presentapplication.

DETAILED DESCRIPTION

The following description contains specific information pertaining toimplementations of the present application. The drawings in the presentapplication and their accompanying detailed description are directed tomerely example implementations. However, the present application is notlimited to merely these example implementations. Other variations andimplementations of the present application will be obvious to thoseskilled in the art. Unless noted otherwise, like or correspondingelements among the drawings may be indicated by like or correspondingreference numerals. Moreover, the drawings and illustrations in thepresent application are generally not to scale and are not intended tocorrespond to actual relative dimensions.

For the purpose of consistency and ease of understanding, like featuresmay be identified (although, in some examples, not shown) by the samenumerals in the drawings. However, the features in differentimplementations may be differed in other respects, and thus shall not benarrowly confined to what is shown in the drawings.

The description uses the phrases “in one implementation,” or “in someimplementations,” which may each refer to one or more of the same ordifferent implementations. The term “coupled” is defined as connected,whether directly or indirectly through intervening components, and isnot necessarily limited to physical connections. The term “comprising”means “including, but not necessarily limited to”; it specificallyindicates open-ended inclusion or membership in the so-describedcombination, group, series and the equivalent. The expression “at leastone of A, B and C” or “at least one of the following: A, B and C” means“only A, or only B, or only C, or any combination of A, B and C.”

Additionally, for the purposes of explanation and non-limitation,specific details, such as functional entities, techniques, protocols,standard, and the like are set forth for providing an understanding ofthe described technology. In other examples, detailed description ofwell-known methods, technologies, systems, architectures, and the likeare omitted so as not to obscure the description with unnecessarydetails.

Persons skilled in the art will immediately recognize that any networkfunction(s) or algorithm(s) described in the present application may beimplemented by hardware, software or a combination of software andhardware. Described functions may correspond to modules which may besoftware, hardware, firmware, or any combination thereof. The softwareimplementation may comprise computer executable instructions stored on acomputer readable medium such as memory or other type of storagedevices. For example, one or more microprocessors or general-purposecomputers with communication processing capability may be programmedwith corresponding executable instructions and carry out the describednetwork function(s) or algorithm(s). The microprocessors orgeneral-purpose computers may be formed of Applications SpecificIntegrated Circuitry (ASIC), programmable logic arrays, and/or using oneor more Digital Signal Processor (DSPs). Although some of the describedimplementations are oriented to software installed and executing oncomputer hardware, alternative implementations implemented as firmwareor as hardware or combination of hardware and software are well withinthe scope of the present application.

The computer readable medium includes but is not limited to RandomAccess Memory (RAM), Read Only Memory (ROM), Erasable ProgrammableRead-Only Memory (EPROM), Electrically Erasable Programmable Read-OnlyMemory (EEPROM), flash memory, Compact Disc Read-Only Memory (CD-ROM),magnetic cassettes, magnetic tape, magnetic disk storage, or any otherequivalent medium capable of storing computer-readable instructions.

A radio communication network architecture (e.g., a Long Term Evolution(LTE) system, an LTE-Advanced (LTE-A) system, an LTE-Advanced Prosystem, or a 5G NR Radio Access Network (RAN)) typically includes atleast one base station (BS), at least one UE, and one or more optionalnetwork elements that provide connection within a network. The UEcommunicates with the network (e.g., a Core Network (CN), an EvolvedPacket Core (EPC) network, an Evolved Universal Terrestrial Radio Accessnetwork (E-UTRAN), a 5G Core (5GC), or an internet), through a RANestablished by one or more base stations.

It should be noted that, in the present application, a UE may include,but is not limited to, a mobile station, a mobile terminal or device, auser communication radio terminal. For example, a UE may be a portableradio equipment, which includes, but is not limited to, a mobile phone,a tablet, a wearable device, a sensor, a vehicle, or a Personal DigitalAssistant (PDA) with wireless communication capability. The UE isconfigured to receive and transmit signals over an air interface to oneor more cells in a radio access network.

A base station may be configured to provide communication servicesaccording to at least one of the following Radio Access Technologies(RATs): Worldwide Interoperability for Microwave Access (WiMAX), GlobalSystem for Mobile communications (GSM) that is often referred to as 2G,GSM Enhanced Data rates for GSM Evolution (EDGE) Radio Access Network(GERAN), General Packet Radio Service (GPRS), Universal MobileTelecommunication System (UMTS) that is often referred to as 3G based onbasic wideband-code division multiple access (W-CDMA), high-speed packetaccess (HSPA), LTE, LTE-A, evolved LTE (eLTE), e.g., LTE connected to5GC, NR (often referred to as 5G), and/or LTE-A Pro. However, the scopeof the present application should not be limited to the listedprotocols.

A base station may include, but is not limited to, a node B (NB) as inthe UMTS, an evolved node B (eNB) as in LTE or LTE-A, a radio networkcontroller (RNC) as in the UMTS, a base station controller (BSC) as inthe GSM/GERAN, a ng-eNB as in an E-UTRA base station in connection withthe 5GC, a next generation Node B (gNB) as in the 5G-RAN, and any otherapparatus capable of controlling radio communication and managing radioresources within a cell. The base station may serve one or more UEsthrough a radio interface.

The base station is operable to provide radio coverage to a specificgeographical area using a plurality of cells forming the radio accessnetwork. The base station supports the operations of the cells. Eachcell is operable to provide services to at least one UE within its radiocoverage. More specifically, each cell (often referred to as a servingcell) provides services to serve one or more UEs within its radiocoverage (e.g., each cell schedules the downlink (DL) and optionallyuplink (UL) resources to at least one UE within its radio coverage forDL and optionally UL packet transmissions). The base station cancommunicate with one or more UEs in the radio communication systemthrough the plurality of cells. A cell may allocate sidelink (SL)resources for supporting Proximity Service (ProSe) or Vehicle toEverything (V2X) service. Each cell may have overlapped coverage areaswith other cells.

As discussed previously, the frame structure for NR supports flexibleconfigurations for accommodating various next generation (e.g., 5G)communication requirements, such as Enhanced Mobile Broadband (eMBB),Massive Machine Type Communication (mMTC), Ultra-Reliable andLow-Latency Communication (URLLC), while fulfilling high reliability,high data rate and low latency requirements. The OrthogonalFrequency-Division Multiplexing (OFDM) technology in the 3rd GenerationPartnership Project (3GPP) may serve as a baseline for an NR waveform.The scalable OFDM numerology, such as the adaptive sub-carrier spacing,the channel bandwidth, and the Cyclic Prefix (CP) may also be used.Additionally, two coding schemes are considered for NR: (1) Low-DensityParity-Check (LDPC) code and (2) Polar Code. The coding scheme adaptionmay be configured based on the channel conditions and/or the serviceapplications.

Moreover, it is also considered that in a transmission time interval(TTI) of a single NR frame, at least DL transmission data, a guardperiod, and an uplink (UL) transmission data should be included. Therespective portions of the DL transmission data, the guard period, andthe UL transmission data should also be configurable, for example, basedon the network dynamics of NR. In addition, sidelink resources may alsobe provided in an NR frame to support ProSe services or V2X services.

The terms “system” and “network” as used herein may be usedinterchangeably. The term “and/or” as used herein is only an associationrelationship for describing associated objects and represents that threerelationships may exist. For example, A and/or B may indicate that: Aexists alone, A and B exist at the same time, or B exists alone. Inaddition, the character “/” as used herein generally represents that theassociated objects are in an “or” relationship.

FIG. 1 is a flowchart of a method 100 for beam failure recoveryperformed by a UE, according to an example implementation of the presentapplication. In action 102, the UE may perform BFD to detect a beamfailure condition in a cell (e.g., an SCell). The UE may be explicitlyor implicitly configured with a set of BFD reference signals (RS), whichmay include a Channel State Information Reference Signal (CSI-RS) and aSynchronization Signal Block (SSB). In one implementation, an explicitconfiguration of the BFD RS may be transmitted via Radio ResourceControl (RRC) signaling. On the other hand, the UE may determine the BFDRS by itself if the BFD RS is implicitly configured. The UE may detectthe beam failure condition by measuring the BFD RS, such as determininga BLock Error Rate (BLER) based on the measurement of the BFD RS. In oneimplementation, each time the determined BLER exceeds a threshold may beconsidered as a beam failure instance, and the UE may declare a beamfailure condition is detected when the number of consecutive beamfailure instances exceeds a specific value.

In action 104, the UE may perform NBI to find a new beam pair link onwhich connectivity between the UE and an associated BS may be restored.The UE may be explicitly or implicitly configured with a set of NBI RS,which may include CSI-RS and/or SSB. In one implementation, an explicitconfiguration of the NBI RS may be transmitted via RRC signaling. On theother hand, the UE may determine the NBI RS by itself if the NBI RS isimplicitly configured. The set of NBI RS may correspond to a set ofcandidate beams. The UE may determine a new candidate beam from the setof NBI RS. In one implementation, the UE may measure the quality (e.g.,L1-RSRP) of the NBI RS to choose the new candidate beam from the set ofNBI RS. It should be noted that the order of actions described in FIG. 1is not intended to be construed as a limitation. For example, action 104may be followed by action 102 in one implementation.

In action 106, the UE may transmit a beam failure recovery request(BFRQ) to a base station after the UE has detected a beam failurecondition. In one implementation, the UE may have identified a newcandidate beam (e.g., in action 104) before transmitting the BFRQ aswell. The BFRQ informs the network that a beam failure has beendetected. In one implementation, the BFRQ may include information aboutthe new candidate beam.

In one implementation, for beam failure that takes place in a specialcell (e.g., a PCell or a PSCell), the BFRQ may be transmitted on aPhysical Random Access Channel (PRACH). In principle, bothcontention-free and contention-based PRACH resources may be used. In oneimplementation, a contention-free PRACH resource may be prioritized overcontention-based PRACH resource. A two-step contention-free randomaccess procedure may include preamble transmission and random accessresponse. In one implementation, each reference signal corresponding tothe different candidate beams may be associated with a specific preambleconfiguration.

In action 108, the UE may receive response from the network. In oneimplementation, a specific control resource set (CORESET) or searchspace is defined for response reception (e.g., CORESET-BFR or aSearchSpace-BFR indicated by a higher layer parameterrecoverySearchSpaceId). The UE may monitor Physical Downlink ControlChannel (PDCCH) transmission on the CORESET-BFR/SeachSpace-BFR todetermine if the BFRQ is successfully received by the network. ADownlink Control Information (DCI) format in theCORESET-BFR/SeachSpace-BFR may be considered as a successful networkresponse. In one implementation, the UE may assume that the network,when responding the BFRQ, is transmitting PDCCH quasi co-located (QCL)with the RS associated with the new candidate beam in the BFRQ.

It should be noted that the term “beam” may be replaced by “spatialfilter”. For example, when the UE reports a new candidate beam (e.g., agNB TX beam), the UE is essentially selecting a spatial filter used bythe gNB. The term “beam information” may represent informationindicating which beam is used or which spatial filter is selected. Inone implementation, individual reference signals may be transmitted byapplying individual beams (or spatial filters). Thus, beam informationmay be represented by reference signal resource indexes.

The previous description relates to PRACH-based BFRQ transmission andnetwork response, which may be used in a special cell BFR procedure. ForBFR in an SCell, the BFRQ transmission in action 106 in FIG. 1 may be on(a) a PRACH, (b) a PUSCH, or (c) a Physical Uplink Control Channel(PUCCH). In one implementation, the BFRQ may be transmitted on thePUSCH. The UE may transmit a BFR MAC CE on the PUSCH to carry the BFRQ.The transmission of the BFR MAC CE may be associated with a HybridAutomatic Repeat Request (HARQ) process having a HARQ process ID. In oneimplementation, the BFRQ (e.g., the BFR MAC CE if BFRQ is transmitted onthe PUSCH) may include a cell index of an SCell in which beam failureoccurs. In one implementation, the BFRQ (e.g., the BFR MAC CE) mayinclude a cell index of an SCell in which beam failure occurs (asdetermined in action 102 in FIG. 1) and a new candidate beam index forthe SCell (as determined in action 104 in FIG. 1). In oneimplementation, the PUSCH for transmitting the BFRQ may be obtained froma preceding scheduling request (SR) transmission via a PUCCH or from aconfigured grant resource.

Several implementations are provided below for the network responseillustrated in action 108 in FIG. 1.

Case 1: Determination of SCell BFR Success—Implicit Response

In one implementation, the UE may consider the BFR proceduresuccessfully completed upon receiving a response from the networkincluding a DCI format that indicates to flush a soft buffer of the HARQprocess ID used to transmit the BFRQ information. In one implementation,the UE may consider the BFR procedure successfully completed uponreceiving a DCI format that schedules a PUSCH transmission with the HARQprocess ID, where the DCI format indicates a toggled New Data Indicator(NDI) value. For example, when the transmission of the BFR MAC CE isassociated with a HARQ process having a HARQ process ID #2 in action106, the UE may determine that the network successfully receives the BFRMAC CE upon receiving the DCI format that schedules a PUSCH transmissionwith HARQ process ID #2 and indicates a toggled NDI value in action 108.In one implementation, the UE may consider the BFR proceduresuccessfully completed upon receiving an uplink grant for a newtransmission (e.g., indicating a toggled NDI value) for the HARQ processused for the transmission of the BFR MAC CE.

In one implementation, the UE may consider the BFR proceduresuccessfully completed upon receiving a MAC CE that indicates a changein a PDCCH Transmission Configuration Indication (TCI) state for theSCell triggering the BFRQ transmission.

In one implementation, after determining that the SCell BFR procedure issuccessfully completed, the UE may receive a PDCCH on the SCell in whichbeam failure occurs with antenna port quasi-colocation parametersassociated with the new candidate beam index in the BFR MAC CE afterreceiving the DCI format indicating a toggled NDI value and schedulingthe PUSCH transmission with the HARQ process ID used for transmission ofthe BFR MAC CE.

FIG. 2 is a flowchart of an example method for SCell BFR performed by aUE, according to an example implementation of the present application.In action 202, the UE transmits, to a base station, a BFR MAC CE thatincludes a cell index of an SCell in which beam failure occurs and a newcandidate beam index for the SCell, where the transmission of the BFRMAC CE is associated with a HARQ process having a HARQ process ID.Action 202 may relate to action 106 for BFRQ transmission in FIG. 1. Inaction 204, the UE receives, from the base station, a first DCI formatthat schedules a first PUSCH transmission with the HARQ process ID thatis used in action 202, where the first DCI format indicates a toggledNDI value. Action 204 may relate to action 108 for response reception inFIG. 1. In one implementation, the UE may consider the first DCI formatin action 204 as an acknowledgement message from the base station,indicating the BFR MAC CE in action 202 has been successfully receivedby the base station. In one implementation, the UE may receive a PDCCHon the SCell with antenna port quasi-colocation parameters associatedwith the new candidate beam index after receiving the first DCI format.

FIG. 3 includes a diagram illustrating an example method for an SCellBFR procedure, according to an example implementation of the presentapplication. In action 330, UE 310 performs beam failure detection andnew beam identification. UE 310 may generate a BFRQ when a beam failurecondition is detected in action 330. In one implementation, the BFRQ maybe a BFR MAC CE that carries a cell index of an SCell in which beamfailure occurs and a new candidate beam index for the SCell. In oneimplementation, UE 310 may transmit a scheduling request (SR) to basestation 320 in action 332 to request an UL resource for transmitting theBFR MAC CE. In one implementation, the SR in action 332 may bededicatedly configured for BFR. The SR may be transmitted on a PUCCH.

In action 334, UE 310 may receive, from base station 320, DCI #1 (e.g.,UL grant) that schedules a PUSCH transmission during which the BFR MACCE may be transmitted. DCI #1 may be transmitted on a PDCCH. DCI #1 maybe associated with a HARQ process ID (e.g., HARQ process #3). DCI #1 mayinclude an NDI value (e.g., 0). In action 336, UE 310 may transmit theBFR MAC CE to base station 320 on a PUSCH scheduled by DCI #1. Thetransmission of the BFR MAC CE in action 336 may be associated with aHARQ process having the HARQ process ID such as HARQ process #3. Inaction 338, UE 310 may receive, from base station 320, DCI #2 (e.g., ULgrant) that schedules a PUSCH transmission with the same HARQ process IDused in action 336 (e.g., HARQ process #3). An NDI value in DCI #2(e.g., 1) is toggled compared to the NDI value in DCI #1 (e.g., 0). UE310 may consider the SCell BFR procedure as successfully completed afterreceiving DCI #2 in action 338.

In one implementation, the PUSCH resource in which the BFR MAC CE istransmitted in action 336 may be allocated by a configured grant ratherthan a dynamic grant such that action 332 and action 334 may be omitted.In addition, if DCI #2 in action 338 is scrambled by a configuredscheduling radio network temporary identifier (CS-RNTI) of UE 310, theNDI value in DCI #2 may be considered toggled irrespective of its value.In other words, in one implementation, DCI #2 may indicate a toggled NDIvalue if DCI #2 is scrambled by CS-RNTI of UE 310 when a configuredgrant is used for the BFR MAC CE, if DCI #2 is not validated asactivation/release command for configured UL type-2 grant.

Case 2: Determination of SCell BFR Success—Explicit Response

In one implementation, the UE may consider the BFR proceduresuccessfully completed upon receiving a DCI format in the CORESET-BFRcorresponding to the SCell in which beam failure occurs. For example,the UE may consider SCell BFR as successful upon receiving the DCIformat within a predetermined or configured time window. The CORESET-BFRmay be a dedicated PDCCH CORESET configured for BFR. The dedicated PDCCHCORESET may be used solely for BFR purpose. In another implementation,the CORESET-BFR may be shared with other purpose in a time divisionmultiplexing (TDM) manner. For example, within the configured timewindow, the CORESET-BFR may only be used for BFR but not others. Thismay be achieved by configuring a dedicated search space which isassociated with the CORESET-BFR for BFR purpose. Since the dedicatedsearch space provide time domain monitoring pattern, the configured timewindow may be implemented this way. In one implementation, theCORESET-BFR may be configured in the SCell in which beam failure occurs.In one implementation, the CORESET-BFR may be configured in anotherserving cell other than the SCell in which beam failure occurs.

In one implementation, the UE may consider the BFR proceduresuccessfully completed upon receiving a MAC CE that indicates successfulreception of a corresponding BFRQ transmission. In one implementation,the MAC CE may carry information to identify with which BFR procedurethe response is associated. For example, the UE may trigger multiple BFRprocedures and the MAC CE in the network response may indicate one ormore of the triggered BFR procedures as successful such as by using anindex or a bitmap. In one implementation, the BFRQ may include multipleSCell indexes when beam failure occurs in multiple SCells and the MAC CEmay carry one or more cell indexes to indicate which SCell BFR procedureis successful.

In one implementation, after determining that the SCell BFR procedure issuccessfully completed, the UE may receive PDCCH on the SCell in whichbeam failure occurs with antenna port quasi-colocation parametersassociated with the new candidate beam index that is carried in the BFRMAC CE.

Case 3: Determination of SCell BFR Failure

In one implementation, the UE may be configured with a BFR timer such asvia RRC signaling. In one implementation, the UE may start the BFR timerupon detecting a beam failure condition. Beam failure detection may bereferred to action 102 in FIG. 1. In one implementation, the UE maystart the BFR timer when the UE transmits the BFR MAC CE. Transmissionof the BFR MAC CE may be referred to action 202 in FIG. 2.

In one implementation, the UE may start the BFR timer when the firstPUCCH with BFR information is transmitted. In one implementation, SRtransmitted in action 332 in FIG. 3 may be the first PUCCH with BFRinformation. In one implementation, the BFRQ may be transmitted on aPUCCH, and the BFRQ on the PUCCH may be the first PUCCH with BFRinformation. The UE may start the BFR timer when the UE transmits theBFRQ on the PUCCH. In one implementation, the BFR timer may be started apredetermined/configured time after the first PUCCH with BFR informationis transmitted. For example, the predetermined/configured time may beone or more symbols or one or more slots. In one implementation, the UEmay start the BFR timer at the beginning of a next symbol or next slotafter the first PUCCH with BFR information is transmitted.

In one implementation, the UE may stop the BFR timer when the UEconsiders the SCell BFR as successful. The network response forindicating a successful SCell BFR may be referred to implementationsprovided in Case 1 and Case 2. In one implementation, the UE (e.g., aMAC entity of the UE) may optionally indicate to a higher layer (e.g.,RRC layer) the success of the SCell BFR.

In one implementation, the UE may consider the SCell BFR procedure asfailed if the network response is not received within a configured timeperiod such as an expiration time of the BFR timer. In oneimplementation, the UE may stop the SCell BFR procedure when the BFRtimer expires and prohibit further BFRQ transmission.

FIG. 4 is a flowchart of an example method for SCell BFR when a UE isconfigured with a BFR timer, according to an example implementation ofthe present application. In action 402, the UE may start the BFR timer.Several implementations regarding when the BFR timer may be started havebeen described previously. In action 404, the UE may stop the BFR timerupon receiving the first DCI format that indicates a toggled NDI valueand schedules the PUSCH transmission with the HARQ process ID used fortransmission of the BFR MAC CE. The UE may consider the SCell BFR assuccessful upon receiving the first DCI format. In action 406, the UEmay stop the HARQ process associated with the transmission of the BFRMAC CE when the BFR timer expires. The UE may consider the SCell BFR asfailed if the network response is not received when the BFR timerexpires.

Case 4: Observing a Network Response

In one implementation, the UE may observe the network response for aBFRQ (e.g., a BFR MAC CE) in the SCell in which beam failure occurs. Inone implementation, the UE may apply the reported new beam informationon all configured CORESET(s)/SearchSpace(s) or on a dedicatedCORESET/SearchSpace in the SCell for response reception. In oneimplementation, the UE may apply beam information that is originallyindicated by the base station (e.g., via TCI activation MAC CE(s) forcontrol channel(s)) on all CORESET(s)/SearchSpace(s) in the SCell forresponse reception.

In one implementation, the UE may observe the network response in anintra-band SCell that is different from the S Cell in which beam failureoccurs. In one implementation, the UE may apply the reported new beaminformation on all configured CORESET(s)/SearchSpace(s) or on adedicated CORESET/SearchSpace in the intra-band SCell for responsereception. In one implementation, the UE may apply beam information thatis originally indicated by the base station (e.g., via TCI activationMAC CE(s) for control channel(s)) on all CORESET(s)/SearchSpace(s) inthe intra-band SCell for response reception.

In one implementation, where the UE observes the network response maydepend on the PUSCH resource for BFRQ transmission (e.g., PUSCH inaction 336) allocated by the UL grant (e.g., DCI #1 in action 334). Forexample, the UE may observe the network response in the cell where thePUSCH resource is allocated. In one implementation, the UE may apply thereported new beam information on all configuredCORESET(s)/SearchSpace(s) or on a dedicated CORESET/SearchSpace in thecell in which the PUSCH resource is allocated for response reception. Inone implementation, the UE may apply beam information that is originallyindicated by the base station (e.g., via TCI activation MAC CE(s) forcontrol channel(s)) on all CORESET(s)/SearchSpace(s) in the cell forresponse reception.

In one implementation, where the UE observes the network response maydepend on network implementation. The network response may betransmitted on any serving cell. In one example, the UE may apply beaminformation that is originally indicated by the base station (e.g., viaTCI activation MAC CE(s) for control channel(s)) on allCORESET(s)/SearchSpace(s) in corresponding cells for response reception.

Case 5: SCell BFR in Cross-Carrier Scheduling

FIG. 5 is a diagram 500 illustrating a cross-carrier scheduling scenarioaccording to an example implementation of the present application. A BS501 may provide coverage over component carrier (CC) #1 and a BS 502 mayprovide coverage over CC #2. As illustrated, cell 512 is cross-carrierscheduled by cell 511. In other words, a PDCCH on cell 511 may includescheduling information of a PDSCH on cell 512. Cell 511 may be referredas a scheduling cell and cell 512 may be referred to as a scheduledcell. In one implementation, cell 512 may be an SCell and cell 511 maybe a PCell, a PSCell, or an SCell.

In one implementation, an SCell BFR procedure may be triggered in cell512 to maintain the control channel quality of CC #2. For example, UE503 may detect a beam failure condition in cell 512 and subsequentlytransmit a BFRQ. In one implementation, a DCI format with a carrierindicator field (CIF) in the scheduling cell (e.g., cell 511) may beconsidered as a network response to the BFRQ of the scheduled cell(e.g., cell 512). It should be noted that various implementations of thenetwork response provided in Case 1 and Case 2 may be combined with theDCI format having the CIF field used in cross-carrier scheduling.

In one implementation, the UE may observe the network response in thescheduling cell (e.g., cell 511). In one implementation, the UE mayapply the reported new beam information on all configuredCORESET(s)/SearchSpace(s) in the scheduling cell for response reception.In one implementation, the UE may apply beam information that isoriginally indicated by the base station (e.g., via TCI activation MACCE(s) for control channel(s)) on individual CORESET(s)/SearchSpace(s) inthe scheduling cell for response reception.

In one implementation, the UE may observe the network response in thescheduled cell (e.g., cell 512). In one implementation, the UE may applythe reported new beam information on all configuredCORESET(s)/SearchSpace(s) in the scheduled cell for response reception.In one implementation, the UE may apply beam information that isoriginally indicated by the base station (e.g., via TCI activation MACCE(s) for control channel(s)) on individual CORESET(s)/SearchSpace(s) inthe scheduled cell for response reception.

FIG. 6 is a block diagram illustrating a node for wireless communicationaccording to the present application. As illustrated in FIG. 6, a node600 may include a transceiver 620, a processor 628, a memory 634, one ormore presentation components 638, and at least one antenna 636. The node600 may also include an RF spectrum band module, a base station (BS)communications module, a network communications module, and a systemcommunications management module, Input/Output (I/O) ports, I/Ocomponents, and power supply (not explicitly shown in FIG. 6). Each ofthese components may be directly or indirectly in communication witheach other over one or more buses 640. In one implementation, the node600 may be a UE or a base station that performs various functionsdescribed herein with reference to FIGS. 1 through 5.

The transceiver 620 having a transmitter 622 (e.g.,transmitting/transmission circuitry) and a receiver 624 (e.g.,receiving/reception circuitry) may be configured to transmit and/orreceive time and/or frequency resource partitioning information. In someimplementations, the transceiver 620 may be configured to transmit indifferent types of subframes and slots including, but not limited to,usable, non-usable and flexibly usable subframes and slot formats. Thetransceiver 620 may be configured to receive data and control channels.

The node 600 may include a variety of computer-readable media.Computer-readable media may be any available media that may be accessedby the node 600 and include both volatile and non-volatile media,removable and non-removable media. By way of example, and notlimitation, computer-readable media may comprise computer storage mediaand communication media. Computer storage media include both volatileand non-volatile, removable and non-removable media implemented in anymethod or technology for storage of information such ascomputer-readable instructions, data structures, program modules ordata.

Computer storage media include RAM, ROM, EEPROM, flash memory or othermemory technology, CD-ROM, Digital Versatile Disks (DVD) or otheroptical disk storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices. Computer storage media do notcomprise a propagated data signal. Communication media typically embodycomputer-readable instructions, data structures, program modules orother data in a modulated data signal such as a carrier wave or othertransport mechanism and includes any information delivery media. Theterm “modulated data signal” means a signal that has one or more of itscharacteristics set or changed in such a manner as to encode informationin the signal. By way of example, and not limitation, communicationmedia include wired media such as a wired network or direct-wiredconnection, and wireless media such as acoustic, RF, infrared and otherwireless media. Combinations of any of the previously listed componentsshould also be included within the scope of computer-readable media.

The memory 634 may include computer-storage media in the form ofvolatile and/or non-volatile memory. The memory 634 may be removable,non-removable, or a combination thereof. Example memory includessolid-state memory, hard drives, optical-disc drives, etc. Asillustrated in FIG. 6, the memory 634 may store computer-readable,computer-executable instructions 632 (e.g., software codes) that areconfigured to cause the processor 628 to perform various functionsdescribed herein, for example, with reference to FIGS. 1 through 5.Alternatively, the instructions 632 may not be directly executable bythe processor 628 but be configured to cause the node 600 (e.g., whencompiled and executed) to perform various functions described herein.

The processor 628 (e.g., having processing circuitry) may include anintelligent hardware device, e.g., a Central Processing Unit (CPU), amicrocontroller, an ASIC, etc. The processor 628 may include memory. Theprocessor 628 may process the data 630 and the instructions 632 receivedfrom the memory 634, and information transmitted and received via thetransceiver 620, the base band communications module, and/or the networkcommunications module. The processor 628 may also process information tobe sent to the transceiver 620 for transmission via the antenna 636 tothe network communications module for transmission to a core network.

One or more presentation components 638 present data indications to aperson or another device. Examples of presentation components 638include a display device, a speaker, a printing component, and avibrating component, etc.

In view of the disclosure, it is obvious that various techniques may beused for implementing the concepts in the present application withoutdeparting from the scope of those concepts. Moreover, while the conceptshave been described with specific reference to certain implementations,a person of ordinary skill in the art may recognize that changes may bemade in form and detail without departing from the scope of thoseconcepts. As such, the described implementations are to be considered inall respects as illustrative and not restrictive. It should also beunderstood that the present application is not limited to the particularimplementations described and many rearrangements, modifications, andsubstitutions are possible without departing from the scope of thepresent disclosure.

What is claimed is:
 1. A user equipment (UE) for performing a SecondaryCell (SCell) Beam Failure Recovery (BFR) procedure, the UE comprising:one or more non-transitory computer-readable media havingcomputer-executable instructions embodied thereon; and at least oneprocessor coupled to the one or more non-transitory computer-readablemedia, the at least one processor configured to execute thecomputer-executable instructions to: transmit, via uplink (UL), to abase station (BS), a BFR Medium Access Control (MAC) Control Element(CE) that includes a cell index of an Scell with beam failure detectedand a reference signal index for the Scell, the UL transmission of theBFR MAC CE associated with a Hybrid Automatic Repeat Request (HARQ)process having a HARQ process identifier (ID); receive, from the BS,Downlink Control Information (DCI) that schedules a Physical UplinkShared Channel (PUSCH) transmission with the HARQ process ID of the HARQprocess that is used for the UL transmission of the BFR MAC CE, the DCIindicating a toggled New Data Indicator (NDI) value; determine, uponreceiving the DCI, that the Scell BFR procedure is successfullycompleted; and monitor, on the Scell, a Physical Downlink ControlChannel (PDCCH) using antenna port quasi-colocation parametersassociated with the reference signal index after receiving the DCI. 2.The UE of claim 1, wherein the at least one processor is furtherconfigured to execute the computer-executable instructions to: applybeam information indicated by the BS via at least one TransmissionConfiguration Indication (TCI) activation MAC CE to receive the DCI. 3.The UE of claim 1, wherein the at least one processor is furtherconfigured to execute the computer-executable instructions to: start,before receiving the DCI, a BFR timer; and stop the BFR timer uponreceipt of the DCI.
 4. The UE of claim 3, wherein the at least oneprocessor is further configured to execute the computer-executableinstructions to: start the BFR timer upon detection of a beam failurecondition.
 5. The UE of claim 3, wherein the at least one processor isfurther configured to execute the computer-executable instructions to:stop the BFR timer when the Scell BFR procedure is determined assuccessfully completed.
 6. The UE of claim 3, wherein starting the BFRtimer before receiving the DCI comprises starting the BFR timer when theBFR MAC CE is transmitted.
 7. The UE of claim 1, wherein the at leastone processor is further configured to execute the computer-executableinstructions to: transmit a Scheduling Request (SR) for BFR.
 8. The UEof claim 7, wherein the SR requests a UL resource for transmitting theBFR MAC CE.
 9. The UE of claim 1, wherein: the toggled NDI value iscompared to an NDI value associated with the BFR MAC CE, and the toggledNDI value is different from the NDI value associated with the BFR MACCE.
 10. A method for a Secondary Cell (Scell) Beam Failure Recovery(BFR) procedure performed by a User Equipment (UE), the methodcomprising: transmitting, via uplink (UL), to a base station (BS), a BFRMedium Access Control (MAC) Control Element (CE) that includes a cellindex of an S cell with beam failure detected and a reference signalindex for the Scell, the UL transmission of the BFR MAC CE associatedwith a Hybrid Automatic Repeat Request (HARQ) process having a HARQprocess identifier (ID); receiving, from the BS, Downlink ControlInformation (DCI) that schedules Physical Uplink Shared Channel (PUSCH)transmission with the HARQ process ID of the HARQ process that is usedfor the UL transmission of the BFR MAC CE, the DCI indicating a toggledNew Data Indicator (NDI) value; determining, upon receiving the DCI,that the Scell BFR procedure is successfully completed; and monitoring,on the Scell, a Physical Downlink Control Channel (PDCCH) using antennaport quasi-colocation parameters associated with the reference signalindex after receiving the DCI.
 11. The method of claim 10, furthercomprising: applying beam information indicated by the BS via at leastone Transmission Configuration Indication (TCI) activation MAC CE toreceive the DCI.
 12. The method of claim 10, further comprising:starting, before receiving the DCI, a BFR timer; and stopping the BFRtimer upon receipt of the DCI.
 13. The method of claim 12, furthercomprising starting the BFR timer upon detection of a beam failurecondition.
 14. The method of claim 12, further comprising: stopping theBFR timer when the Scell BFR procedure is determined as successfullycompleted.
 15. The method of claim 12, further comprising starting theBFR timer before receiving the DCI comprises starting the BFR timer whenthe BFR MAC CE is transmitted.
 16. The method of claim 10, furthercomprising: transmitting a Scheduling Request (SR) for BFR.
 17. Themethod of claim 16, wherein the SR requests a UL resource fortransmitting the BFR MAC CE.
 18. The method of claim 10, wherein: thetoggled NDI value is compared to an NDI value associated with the BFRMAC CE, and the toggled NDI value is different from the NDI valueassociated with the BFR MAC CE.